Method and apparatus for drying harvested crops prior to storage

ABSTRACT

Reduction of moisture in harvested crop particles such as corn and soy beans. Waste heat from an internal engine carried by a harvester is applied to the crop during the harvesting process. Microwave energy is optionally applied to the crop, concurrently with application of the heat, or separately from it. The objective is to reduce the moisture to a level acceptable to a storage facility, or at least to reduce the cost of further reduction.

FIELD OF THE INVENTION

[0001] Reducing moisture on and in harvested crops prior to theirstorage.

BACKGROUND OF THE INVENTION

[0002] The harvesting and storage of crops, and especially the storageof crops for a substantial period of time, is heavily affected bymoisture of the atmosphere and of the moisture within the collected cropitself. Crops are harvested while under widely varying atmosphericconditions. Heavy dew, recent rain, and drought are examples ofcircumstances faced by harvesters of field crops due to atmosphericconditions. In addition, the moisture content in the particles of crop,for example inside the outer membrane of a grain of corn, count as partof the moisture of concern. The subsequent storage of a crop instructures such as elevators and silos is highly sensitive to moisturecontent from any source, and these structures can tolerate moisturelevels only below certain threshold values relating to integrity of thecrop and of the structure itself.

[0003] For example, when corn is to be stored after harvest, it iscommon practice for an elevator to refuse to store grain with a totalmoisture content greater than 14%. of course a crop which is brought tothe elevator might have a moisture content higher or lower than that,but if it is higher, the elevator proprietor will either refuse to storeit, or will levy a surcharge to pay for him to reduce the moisturecontent to an acceptable level. This is a substantial surcharge whichthe farmer will much prefer to avoid. Furthermore, the reduction ofmoisture is generally done with heated air, whose heat is derived from apropane flame. The cost for this process is a function of how muchmoisture needs to be removed, and of course on the current unit price ofpropane. In whatever event, the requirement for heat involves anuncertain expense that cannot be predicted, and also involves release ofcarbon compounds into the atmosphere that is subject to regulation whichis certain to become even more stringent.

[0004] It should be remembered that it is not the object of theinvention to “dry” the crop in the sense of desiccation. Crops withmoisture are regularly and routinely stored. The function of thisinvention is to bring down the moisture level to or toward an acceptablelevel by affordable means.

[0005] Increased fuel cost and environmental adversity are not the onlyobjectionable complications of moisture content in the crop. Theunavoidable additional physical handling of the crop required by themoisture-removing process can lead to degradation of the physicalcharacteristics of the crop itself, such as by causing bruising,scratching and fragmentation of the product. This invention minimizesthose risks.

[0006] It is an object of this invention to utilize the combination oftwo moisture-reducing techniques which, when used together result in asurprising reduction of moisture compared to the comparable use of oneof them alone, or each separately.

[0007] In addition, and as an optional objective, use can be made in thefield, on the harvester itself, of an inherent source of heat which incurrent practice is wasted to the atmosphere, or at best a very smallamount is directed to heating the operator's cabin. By heat-treating thecrop with waste heat from the engine while the crop is being harvested,the requirement for a later moisture reduction can be significantlyreduced, and sometimes eliminated entirely. This also can reduce thehandling of the crop.

[0008] This invention thereby provides a means to improve a harvestedcrop not only just before storage, but if desired also while it is beingharvested, so that with less handling and less fuel cost, the crop canbe made ready for storage.

BRIEF DESCRIPTION OF THE INVENTION

[0009] In this specification, the harvesting and treatment of corn isprovided as an example for illustration purposes. The invention isapplicable also to any other crop that can be stored in elevators orsilos. Examples of other crops with which this invention is useful aresoybeans, wheat and rye.

[0010] According to this invention, the harvested crop, for exampleshelled corn, is heated to reduce its moisture should existing moistureof the crop as harvested in the field exceed levels acceptable forstorage. The heat can be provided in two forms: first, a heatedairstream flowing over and through the crop, and second, microwaveenergies injected into the crop at frequencies which are utilized tovaporize water. Such frequencies are commonly utilized in microwaveovens.

[0011] The heating effect of these frequencies resides in thevaporization of water in the product to be heated. While thesefrequencies are effective for removing surface moisture, their greatervalue in this invention is for vaporizing water inside the particles ofproduct themselves. This energy can be applied independently of a heatedairstream.

[0012] According to a preferred but optional feature of the apparatusand method, the apparatus is mounted to or towed along with a harvesterwhile it is harvesting the crop. Exhaust heat from the harvester engineis utilized to heat an airstream which flows over, into, and through thecrop as one step in drying the crop. Conventionally this engine heat iswasted to the atmosphere by cooling the radiator or in the exhaust gasesfrom the engine. In this embodiment, engine heat developed in excess ofmotive requirements is not wasted. Rather it is used beneficially. Ifdesired, an auxiliary source of heat, even a burner can be used alongwith it, or separately, or a somewhat larger engine than is needed forpropulsion and operation of the harvesting machinery may be installed.

[0013] Energy in the two forms is preferably applied simultaneously, sothe flowing heated airstream can assist in removing vaporized waterwhich has passed from the inside of the particle to the outside of it,and can be carried away in the airstream, along with such water asexisted on the surface of the crop when the crop was harvested.

[0014] Advantages are provided by exerting the microwave energy at leastsome of the time while engine heat is also being applied. It is bestpractice to start both of them as soon as possible, preferably in thefield. Preheating the crop with hot gas before treating it withmicrowave energy also provides advantages.

[0015] As a consequence of any of the available arrangements, the farmerhimself is enabled to reduce the moisture in the crop with least damageto the crop, and without any surcharge (or at least only with a reducedsurcharge) to be paid at the elevator. The potential savings are in factquite large, and go straight to the farmer's bottom line. Again it isemphasized that the objective is to reduce moisture to an acceptablelevel, rather than to “dry” the crop.

[0016] It is an additional preferred but optional feature of theinvention to reduce physical wear on the crop as it is being handled, byutilizing a fluidics system for moving the harvested crop instead ofusing the mechanical rotary-type augers or buckets that areconventionally used to propel the crop in a harvester system beyond thethresher head.

[0017] The above and other features of this invention will be fullyunderstood from the following detailed description and the accompanyingdrawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIGS. 1A and 1B are edge to edge schematic showings of the systemaccording to this invention;

[0019]FIG. 2 is a cross-section of a portion of a fluidic lift showed inFIG. 1; and

[0020]FIG. 3 is a cross-section taken at line 3-3 in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

[0021] A detailed description of a harvester construction (frequentlycalled a “combine”) is not necessary for an understanding of thisinvention. In fact, this invention is intended to be an accessory to astandard combine.

[0022] A typical combine has a chassis equipped with tires, transmissionand propulsion devices such as an internal combustion engine supportedon wheels driven by an internal combustion engine 23 through aconventional transmission. Engine 23 characteristically produces astream of hot exhaust gases from its combustion cylinders, and itscoolant system produces heat that is usually dissipated to theatmosphere by its radiator. Both provide a stream of heated air. Thespecific relationship of the combine to this invention is its capacityto carry or tow the harvested crop, and to provide from its engine asource of heat useful for the reduction of moisture in the crop. The twosources of heated air are the engine coolant and the engine exhaustgases.

[0023] The exhaust gases are not intended to be applied to the cropitself because of their pollutant load. There can be no direct contactwith the crop. Instead, heat exchangers are provided which extract theheat from both of these sources. A typical engine radiator is a suitabledevice for the liquid/gas transfer of engine heat to an incoming ambientairstream. Any suitable gas/gas heat exchanger can be utilized toexchange heat from the exhaust gases to an incoming ambient airstream.

[0024] The intended destination of the heated airstream from either ofthese sources is arbitrary and will often be decided by convenience oflocation of the source and destination. Therefore this invention is notto be limited by the particular arrangements shown herein, but it doesshow a preferred arrangement for at least one very popular combine.

[0025] The details of a harvesting head are of no importance to thisinvention. The cutting devices themselves are not shown in the drawings.The harvested crop to be stored, for example shelled corn, are collectedby a lateral auger 25, which is a helically-surfaced rotating body thatconveys the harvested crop to a receptacle. This invention begins afterthis auger, as will later become apparent.

[0026] Internal combustion engine 23 constitutes the power source forthis entire system, as well as for propelling the combine and foroperating its crop-cutting and gathering equipment. Requirements canvary from crop type to crop type and from one size to another of combineand its accessories.

[0027] A crop bin 30 is mounted to the chassis at its side. If desired,the bin can instead be mounted on a towed vehicle carried at the side ofor behind the chassis, as preferred.

[0028] A harvesting head is mounted to the front of the chassis. It hasa width sufficient to harvest a suitable number of rows of crops, or awidth of path when the crops are not in rows. Such heads have means togather and guide the crop to cutters, and threshers to separate theultimate crop value from its burden such as stalks, stems, and cobs. Itsoutput is supplied to the auger.

[0029] The value output of the harvester is the crop to be stored. Themoisture of the harvested crop is the concern of this invention.

[0030] Engine 23 is schematically illustrated with an air inlet 35, afuel inlet 36, an exhaust gas outlet 37, and a heat exchanger 38. Heatexchanger 38 has an ambient air intake 39, and a heated air outlet 40. Ablower 41, perhaps a radiator fan, moves air through the heat exchangerto be heated for use with this invention.

[0031] Heat exchanger 38 captures heat generated by the engine which isconveyed to exchanger 38 by engine coolant through grid 42. Part of theheat exchanger will be recognized as the radiator (or part of aradiator) conventionally provided with an internal combustion engine.Heated air exits from the exchanger 38 through heated air outlet 40.

[0032] Exhaust heat exchanger 43 is most conveniently formed in twosegments joined in series. It will be recognized that a differentplumbing arrangement can be provided instead.

[0033] First segment 44 has an exhaust gas inlet 45 which receivesexhaust gas from the engine through conduit 46. An exhaust gas outlet 47is connected to the exhaust gas inlet 49 of second segment 48 by conduit50. The exhaust gas outlet 51 of second segment 48 connects to anexhaust control device 52 such as a muffler, which in turn discharges toatmosphere.

[0034] A blower 60 provides ambient air under pressure through conduit61 to the air inlet 62 of first segment 44. Air heated in the firstsegment exits through heated air outlet 63 to a conduit 64 which in turnis connected to a fluidic pump 65.

[0035] A blower 67 provides ambient air under pressure through conduit68 to the air inlet 69 of second segment 48. Air heated in the secondsegment exits through heated air outlet 70 through a conduit 71 which inturn is connected to auger 25 for the optional purpose of pre-heatingthe crop to be treated in this system.

[0036] A third blower 75 supplies coolant air through conduits 76, and77 for cooling magnetrons yet to be described. An exhaust blower 79withdraws air from treatment chamber 78 through a vent port 81.

[0037] The foregoing description relates to circulation of air throughthe system, and the capture of heat from the engine coolant and from theengine exhaust gases. The circulation of the crop through the systemfrom the harvester head will now be described.

[0038] Treatment chamber 78 is preferably mounted to the chassis. Foradaption to modern harvesters, it is convenient for the crop to passthrough the chamber vertically downward. Generally it will be preferablefor the chamber to have two opposed space-apart parallel walls joinedtogether at their sides, tops and bottoms. Full details of constructionwill be provided below. For present purposes, it is sufficient todisclose a heated air inlet 80 and vent port 81 into and from thechamber to allow for injection of heated air from fan 41 through conduit82 into the chamber, and venting of the air from the chamber throughvent port 81, thereby to provide a flow of heated air through the cropas it flows downwardly through the treatment chamber. The heated airflow may be counter-current if preferred.

[0039] A microwave source 85, for example two groups of magnetrons, isdisposed adjacent to the treatment chamber. Only one group is shown inthe drawings. The other group is on the other side of the treatmentchamber directed into the treatment chamber. Their radiation is directedinto the crop inside the chamber. They do not directly contact the crop.Ambient air from blower 75 flows over the magnetrons, from conduits 76and 77 to cool the magnetrons.

[0040] A fluidic lift 90 lifts the crop from the thresher to thetreatment chamber and discharges the crop into it.

[0041] As will later be described, the lifts are pneumatic, of a typecharacterized as “fluidic”. This class of flow is surprisingly effectivefor conveying particulate material such as shelled corn with minimalphysical abrasion and with least energy needed to transport it.

[0042] At this point, a few comments about the nature of the crop, themoisture-reducing process, and fluidics will assist in an understandingof the invention.

[0043] Moisture content in the sense in which the term is used in thisart relates to water inside the crop particles and on the outside of thecrop particles in all conditions of handling and storage. Water on thesurface of a wet crop is readily understood. However, there appear to beother ways in which water is contained within the particulate materialwhich forms the crop, and which are measured by persons who store thecrop. An example is kennels of corn. Here it appears that water is boundin various ways in the skin itself, in the cellular material enclosed bythe skin, and perhaps between the cells themselves.

[0044] In whatever form and condition, the water as it exists in thecrop is still measured by a meter such as the hand-held Model 500 ofEaton AG Electronics Control Division, Carol Stearn, Ill. 60188. Thismeter operates on a capacitance measurement concept and measures thetotal gross moisture however it exists. It is generally accepted in theelevator trade for measuring moisture in corn, soy beans, and othergrain crops. It is used to determine the surcharge for too-moist crops.For other crops, different measuring means may be needed. The identityof the measuring device is not part of this invention.

[0045] It is a fact that heating any crop long enough and at high enoughtemperatures will dry it out. However, the inventors herein have learnedsome surprising facts about the drying process. Heated with air for aspecific length of time, the moisture will initially be reduced. Left tostand for a number of minutes after the heating is stopped, the moisturepercentage will continue to decline to some lower value because the cropis still warm.

[0046] In contrast, depending on the intensity of the microwaveradiation, heating with microwave radiation alone for the same length oftime is not usually as effective in reducing the moisture, either as toimmediate reduction of moisture or as to ultimate lower level achievedafter a short delay. However, after a substantial repose period, themoisture level will reduce some more.

[0047] Surprisingly, heating simultaneously with both modes (heated airand microwave) for the same length of time, may not result in a lesserimmediate reduction than when either is used alone. In fact it sometimesis less than when either of them is used alone. However, after the croprests a while after the heating is stopped, there is an unexpectedlylarger ultimate reduction in moisture content, to a level lower thanwhen either was used alone under the same conditions.

[0048] The precise reason for this surprising result is not known, or atleast is not fully understood. For whatever reason, after a “rest”interval the combination of the two modes provides a significantlyenhanced reduction of total moisture. Combined with the use of fluidictransfer techniques, there is much less degradation of cellularstructure, cooking of the product, or abrasion.

[0049] Extensions of these test results indicate that exertion of bothmodes together result in reductions which are greater than would beexpected from use of either one alone. Use of both modes for asufficient length of time is to be encouraged. For reasons to beexplained, advantages can be attained by later application of anairstream, as well as by pre-heating of the crop.

[0050] Reference is made to fluidic lift 90. On a commercial thresher,the thresher head classically has a screw-type auger to move thethreshed crop and its burden away from the head and toward the locationof further processing or disposal. This portion of a thresher isunavoidably rough on the product, and cannot be avoided. The plant hasbeen cut from its roots, the stems and stalks removed, and in thesituation with corn, the head of corn has been husked, and the kernelshave been removed from the cob. The cobs are disposed of along with theremainder of the trash. The kernels (shell) have had a rough passage,and it is an object of this invention to make the remainder of the tripto storage as benign as possible.

[0051] In a system such as this one, the internal transport of productfrom location to location can be important. Crops when harvested can bein varying conditions of hardness or firmness, and their manipulationcan lead to distortion, fragmentation and disruption if excessive forceis applied. However, once these necessary acts are concluded, whatremains is the value of the entire operation and it should be handled asgently as is consistent with high-volume, high strength, rapidly movingmachines.

[0052] The crop is fed by auger 25 to a surge receptacle 65. From thisreceptacle it is to be conveyed to the treatment chamber through lift90. The crop will preferably have been preheated while in the auger fromthe second segment 48 of heat exchanger 43. This can remove significantamounts of surface water from the crop, and can do at least somepre-heating of the crop itself.

[0053] The intake end 95 of the first fluidic lift will preferably bebelow the top level of crop in the receptacle. However, this is notnecessary because of the way the lift operates.

[0054] The lift is “powered” by heated air from first segment 44 of heatexchanger 43. It is supplied to the lift through conduit 64. Beingheated, this air will not only power the lift, but will apply heat tothe crop as the crop travels through the shaft 96 of the lift.

[0055] As best shown in FIG. 2, this lift does not apply a pneumaticforce across the full cross-section of the shaft, Instead, it exerts astrong flow along the inside wall 97 of the shaft at the inlet end. Theinlet end has an open central entry port 99, which is surrounded by aring-like plenum 100 which receives heated air from conduit 64.

[0056] Surrounding the inlet end is a re-entrant groove 101 whichreceives air from the plenum and discharges it in a cylindricalsheet-like pattern along the inside wall 97 of the shaft. Givensufficient volume and rate of flow, this air flow will entrain cropparticles at the entry port and convey them through shaft 96 to theintake 80 of treatment chamber 78.

[0057] Observation of the flow of particles shows a reduction oftumbling and turbulence of the crop. Fractures and abrasions areremarkably reduced compared to results when screw feeds or the morecommon types of pneumatic feeds are used. Furthermore, the particles areheated by this propulsive air flow which is especially useful in heatingwater in the surface of the crop particles.

[0058] When the particles reach the inlet port, they will be distributedby a spreader (not shown) to cover the top of the crop already in thechamber. Gravity flow is sufficient. The crop deposited on the top willreplace crop removed through the exit port or ports 81 at the bottom.From there the particles will be deposited, perhaps directly in bin 30,or perhaps be moved by another fluidic lift to a distant bin.

[0059] Application of surface heat, such as by heated air will removemoisture from a crop. In fact this is what is done at the elevator toreduce moisture in the crop. The ways to accomplish this to a desiredextent are either to raise the temperature considerably for a shortertime, or to keep the temperature low for a longer time. For many cropsthis is akin to cooking them. It should be kept in mind that moisture inthe interior of the crop is also measured by the instruments, and that asufficient temperature must be reached so that there is a gradienttending to move internal moisture out through the skin or other outsidemembrane. To keep the temperatures within reason when gross externalheating is used, the process can be undesirably slow and of longduration, which can affect the crop itself.

[0060] According to this invention, the internal moisture is vaporizedby microwave radiation. This internal vaporization, which need not heatthe entire particle to a very hot temperature, will cause the vapor tomove toward and through the outer membrane. Certainly it is faster thanheating the particles from the outside. It does not require a higherskin temperature to raise the internal temperature.

[0061] For best results, a heated airstream and microwave radiation aresimultaneously applied to the crop in the treatment chamber. It ispossible to apply these treatments separately, but significantadvantages will be lost. For example, when the vapor created in theinside of the particle by the microwave energy reaches the outside ofthe particle, it is advantageous for it to be swept away by the heatedairflow, even while the airflow exerts its own heating effect on theparticle.

[0062] The flow rate of crop through the treatment chamber is controlledby gates (not shown), at the entry and exit of the chamber, or both.Dampers and diverter valves can be provided to adjust air flow among thevarious conduits.

[0063] Also, heat from the engine radiator can be utilized instead ofheat from the exhaust gases, or they can be mixed together.

[0064] As to the parameters of the system, the temperature of theairstream arriving at the heater chamber will ordinarily be above 100degrees F. for shelled corn. The selected temperature may be higher orlower for other crops, but the limits will readily be recognized byagronomists. Generally a temperature of at least 100 degrees F. shouldbe provided. If necessary, supplementary heat may be provided, forexample from an on-board propane heater with its own heat exchanger, butthis will rarely be necessary.

[0065] The microwave radiation is that which is used for ordinarymicrowave ovens. Such ovens function by vaporizing water. The mostuseful frequencies are about 900 MHZ and 2.45 GHZ, and can be providedby the emitters in this invention. Their water vaporizing effects aregenerally known. 900 MHZ is the favored frequency. It is most frequentlyused for vaporization of water and may be used alone. The 2.45 GHZfrequency is regarded as less efficient, but can be used alone or withthe other. These frequencies are effective on all water, inside oroutside of the particles.

[0066] The beams of frequencies 900 MHZ and 2.45 GHZ of course includeother nearby frequencies. Such beams are comprised mostly of thesefrequencies, with lesser amounts of nearby frequencies, as normallyencountered commercially. However, the frequencies content of the beamsis primarily of these.

[0067] While either frequency can be used alone, surprisingly favorableresults can be obtained. The reasons are uncertain, but the results arenot. One is entitled to theorize that the beat frequencies of two mixedfrequencies may be important. Also, because the beans encounterdifferent surfaces and different materials. They may and will interactwith one another in unpredictable ways.

[0068] Critical observations of results when either frequency is usedalone and when both are used together, clearly show an improvement whenthey are used together.

[0069] There has now been described the framework of the system. Crop isharvested and conditioned by the harvester in a routine manner,producing a particulate product with moisture content which depends onthe wetness of the field being harvested, and on the inherent moisturewithin the crop itself. The inherent moisture varies with the growingconditions and the time when in the maturing cycle the crop washarvested.

[0070] The crop is conveyed to the fluidic pump for further processing.Pre-heat can be applied both in the auger and in the fluidic pump toaccelerate the drying process. It is best practice to provide the cropto the treatment chamber at an increased temperature, and after theremoval of at least some of the external moisture by the heated air.

[0071] The crop in the treatment chamber is further treated withmicrowave energy and preferably also with heated air. From the treatmentchamber, the crop is deposited in a bin from which it will ultimately bedelivered to an elevator for storage. It may be useful to continue toapply heated air to the crop after the microwave to remove any waterwhich may have continued to leave the crop particle. Heated air suppliedto a temporary storage bin is a preferred, post microwave moistureremoval technique.

[0072] A preferred feature of this invention is its use of heat whichotherwise would be wasted, at a time in the process when it can mosteffectively reduce the moisture. Even in initial storage, when a laterreduction at the elevator would still be needed, the storage of a crop,even when in transit is better when the crop is not as wet, and containsless moisture in its particles.

[0073] Waste heat from engine coolant and engine exhaust are twosources, which through heat exchangers can be used concurrently oroptionally in any part of the system.

[0074] As a further advantage, the power to drive the magnetrons can bederived from the engine's generator (alternator), which itself in turngenerates heat that is recovered from the engine coolant and engineexhaust. The net fuel requirement for the magnetrons is thereby reducedby the recovery of heat which is heating the crop with a heatedairstream.

[0075] A separate or larger generator than is usually provided with theharvester may be needed to power the magnetrons.

[0076] The economic savings enabled by capture and use of engine heat,while attractive, are not the only, and perhaps not the most importantadvantages of this invention. Instead, the gentle treatment and promptremoval of moisture at the time of harvest, especially from the insideof the crop particle itself, may be more important.

[0077] Because the moisture in crops such as shelled corn can and willchange appreciably during harvesting, processing, storage, and eventesting, it is difficult to produce accurate comparative test results.However, observations made over a significant period of time and withvarious parameters, enable one to make some generalized statements whichare of importance to this invention.

[0078] Treating the crop in the treatment chamber with the use only ofheated air or only with microwave energy will reduce the moisturecontent of the crop by a significant amount. It is interesting toobserve that in both situations there is a rather rapid decrease,followed during a rest period afterward by a further smaller decrease.It is apparent that during the “rest” period, vaporized moisture causedby heating of the crop will continue to leave, but at a relatively lowrate.

[0079] The processing of crops by a thresher is not a slow one. Rates ashigh as 25 bushels of shelled corn per minute are known. This processresponds favorably to a wide range of processing speeds.

[0080] Treating the crop only with microwave, but without heated air (orin some tests without any airflow at all), the moisture will be reduced.Then during a rest period it will reduce further. The reduction willusually stop in less than 45 minutes. Generally the moisture contentwill be less than if the crop had been treated only with heated air.Treatment, first with heated air, and then with microwave, will resultin a reduction of moisture to a level below that of either one appliedseparately. This is more than merely an increased application of both,and is not merely additive. In fact, its results are uniformly better,but randomly so.

[0081] The circumstances are surprisingly favorable if in the treatmentchamber both processes are applied simultaneously. Then some unexpectedconsequences arise. In the treatment chamber there is a continuous flowof heated air across the surfaces of the crop particles. It is temptingto observe that this is the same as heating only with heated air. But itis not the same when microwave energy is simultaneously applied. Thenthe vaporization of surface water on the particles (including moisturein the outer membranes) is accelerated. The heated air then has a lessertask of vaporizing the water, and a larger task of transporting thevapor away from the particle and out of the treatment chamber.

[0082] Even more importantly, the task of the microwave energy isreduced if there is preheat before the particles have reached thetreatment chamber. They are warmer to start with, as is the moisture ontheir surface.

[0083] Now the microwave energy can be applied to moisture within theparticles—inside and in the external membranes, and in the material ofthe particle itself. This moisture is vaporized, but is still containedinside the external membrane. To escape it must pass through themembrane.

[0084] The effect of heated air is to heat the internal structure fromthe outside, which is rather gradual because it is caused by conduction.To achieve a given elevated temperature in the particle requires a muchhigher temperature nearer the surface, and this can adversely affect adelicate crop.

[0085] With microwave energy the situation is different, because theenergy penetrates the particle when applied at an appropriate frequencyand intensity. The result is heating throughout, but without requiringthat a surface temperature higher than the internal temperature bedeveloped. The result is, in a particle at a potentially lowertemperature, all or most of the moisture is vaporized, and all of it isbiased toward a lower concentration and temperature outside. There is apositive tendency for the moisture to leave the particle, and within ashort period of time. Then, because there is a flow of heated air pastthe particles, this moisture is not condensed, but instead is carriedaway by the warm airstream.

[0086] There is a marked reduction of moisture to a value less than whatis accomplished by either mode (heated air or microwave radiation).Experience has shown that the simultaneous exertion of the two modes isof importance. When used on a harvester, there is only a limited periodof time for this process, largely because the volume of the harvestedcrop is significantly larger than the volume of the treatment chamber.When used along with a harvester, this system must have a commensuratecapacity, It is, of course possible to use this system as apre-treatment in conditions that are so adverse that sufficientreduction of moisture for the elevator can not attained in the field.Then supplementary drying, perhaps at the elevator will be needed.

[0087] Still it has been found that with a sufficient simultaneousapplication of heated air and microwave energy, followed by a brief restperiod, very often a crop which would be refused by an elevator withoutfurther treatment will be acceptable without any.

[0088] This invention is not to be limited by the embodiments shown inthe drawings and described in the description, which are given by way ofexample and not of limitation, but only in accordance with the scope ofthe appended claims.

I claim:
 1. Apparatus for reducing the moisture content of harvestedcrops comprising: a treatment chamber having a path of movement of cropparticles therethrough, said chamber having a particle entry port and aparticle exit port spaced apart from one another, between which saidcrop particles pass along a path of particle flow; a magnetron mountedto said treatment chamber so disposed and arranged as to emit microwaveenergy into said crop particles and vaporizing at least some of theirmoisture as the particles flow through the chamber; a source of heatedair, said treatment chamber having a heated air inlet and a heated airoutlet spaced apart from one another and so disposed and arranged thatheated air from said source flows through said crop particles, warmingthem as they flow through the chamber and vaporizing water on theparticles; whereby the heated air stream sweeps with it water which hasbeen vaporized by said heated air and also by the microwave energy. 2.Apparatus according to claim 1 in which said apparatus is mounted to aharvester, and receives crop particles as they are being harvested, saidtreatment chamber exit port discharging said crop particles to acollector.
 3. Apparatus for reducing the moisture content of freshlyharvested crop particles produced by a harvester which includes aharvester head that produces crop particles while the harvester passesthrough a crop field, said harvester including a chassis, an internalcombustion engine which develops waste heat as it operates, and an aircompressor, said apparatus receiving said crop particles from theharvester head, said apparatus comprising: a treatment chamber having apath of movement of crop particles therethrough, said chamber having aparticle entry port and a particle exit port spaced apart from oneanother, between which said crop particles flow along a path of particleflow; a magnetron mounted to said treatment chamber so disposed andarranged as to emit microwave energy into said crop particles andvaporize at least some of their moisture as the particles flow throughthe chamber; said treatment chamber having a heated air inlet and aheated air outlet spaced apart from one another and so disposed andarranged that heated air will flow through said crop particles, warmingthem as they flow through the chamber. a first heat exchanger capturingwaste heat from engine coolant; a second heat exchanger capturing wasteheat from engine exhaust gas; said heat exchangers receiving air underpressure from said air compressor to provide streams of heated air, atleast one of said streams discharging heated air into the heated airinlet of the treatment chamber; a fluidic lift accepting crop particlesfrom the harvester head and propelling and conveying them to theparticle entry port of the treatment chamber, at least one of saidstreams of heated air discharging into said fluidic lift to propel thecrop particles toward said particle entry port; whereby heated air inthe fluidic lift preheats the crop particles as they pass through thefluidic lift, microwave energy vaporizes water in the crop particles inthe treatment chamber, and heated air entering the heated air inletfurther warms the crop particles in the treatment chamber and sweepswith it water which has been vaporized by said heated air and also bythe microwave energy.
 4. Apparatus according to claim 3 in which saidtreatment chamber and fluidic lift are mounted to said chassis, saidtreatment chamber particle exit port discharging crop particles to acollector.
 5. Apparatus according to claim 4 in which said fluidic liftcomprises a cylindrical tube having an open entry end and an open exitend, a plenum surrounding said entry end which receives heated air fromone of said streams, a re-entrant lip inside said tube at said entryend, said lip including a flange spaced from the inner wall of said tubeand directed away from said entry end, said lip forming a channel whichreceives heated air from said plenum, whereby to direct a cylindricalstream of heated air into the tubing tending to draw crop particles intosaid tube and to propel and convey them toward said exit end while alsowarming the particles, and delivering them to the particle entry port ofthe treatment chamber.
 6. Apparatus according to claim 3 in which aplurality of said magnetrons is mounted to said treatment chamber in arow paralleling said path of movement of said crop particles. 7.Apparatus according to claim 3 in which said treatment chamber andfluidic lift are mounted to said chassis, said treatment chamberparticle exit port discharging to a collector.
 8. Apparatus according toclaim 7 in which said fluidic lift comprises a cylindrical tube havingan open entry end and an open exit end, a plenum surrounding said entryend which receives heated air from one of said streams, a re-entrant lipinside said tube at said entry end, said lip including a flange spacedfrom the inner wall of said tube and directed away from said entry end,said lip forming a channel which receives heated air from said plenum,whereby to direct a cylindrical stream of heated air into the tubingtending to draw crop particles into said tube and to propel and conveythem toward said exit end while also warming the particles, anddelivering them to the particle entry port of the treatment chamber. 9.Apparatus according to claim 8 in which a plurality of said magnetronsis mounted to said treatment chamber in a row paralleling said path ofmovement of said crop particles.
 10. A fluidic lift for propelling andconveying crop particles, said fluidic lift comprising a cylindricaltube having an open entry end and an open exit end, a plenum surroundingsaid entry end which receives compressed air, a re-entrant lip insidesaid tube at said entry end, said lip including a flange spaced from theinner wall of said tube and directed away from said entry end, said lipforming a channel which receives compressed air from said plenum,whereby to direct a cylindrical stream of air into the tubing tending todraw crop particles into said tube and to propel and convey them towardsaid exit end.
 11. The method of reducing water content in freshlyharvested crop particles in a treatment chamber having spaced apartwalls with an air inlet port and an exit port, said ports being spacedapart, there being a path for flow of crop particles from inlet port toexit port, a heated air inlet port and an outlet port for supplying astream of heated air to said heated air inlet port, a magnetron sodisposed and arranged as to emit microwave energy into said cropparticles as they pass through the treatment chamber, said methodcomprising: continuously supplying a stream of crop particles to saidtreatment chamber inlet port and removing particles through said exitport which have passed through said treatment chamber, simultaneouslyinjecting a heated air stream into the treatment chamber whileexhausting the air stream through the air outlet port, and alsosimultaneously emitting microwave energy into the crop particles,thereby heating said crop particles and exhausting from said treatmentchamber water which has been vaporized by the heated air and by themicrowave energy.
 12. The method of claim 11 in which the crop particlesare pre-heated before being placed in said treatment chamber.
 13. Themethod of claim 12 in which the pre-heating is accomplished by a heatedair stream which propels the crop particles through a fluidic lift. 14.The method according to claim 11 in which said crop particles arereceived from a harvester head while it is harvesting a crop.
 15. Themethod according to claim 11 in which the magnetron emits microwaveenergy in either one or both of 900 MHZ and 2.45 GHZ.
 16. The methodaccording to claim 11 in which the crop particles are left at rest afterexiting the treatment chamber to enable moisture to migrate which wasnot carried away the air stream.
 17. The method according to claim 11 inwhich the airstream is heated by waste heat from a combustion engine.